How to count occurrences of a char\string within a string?

Question

I want to count how many /s I could find in a string. There are several ways to do it, but I couldn't decide on what the best (or easiest) is.

At the moment I'm going with something like:

string source = "/once/upon/a/time/";
int count = source.Length - source.Replace("/", "").Length;

Or for strings where length > 1:

string haystack = "/once/upon/a/time";
string needle = "/";
int needleCount = ( haystack.Length - haystack.Replace(needle,"").Length ) / needle.Length;

Answer 1

If you're using .NET 3.5 you can do this in a one-liner with LINQ:

int count = source.Count(f => f == '/');

If you don't want to use LINQ you can do it with:

int count = source.Split('/').Length - 1;

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You might be surprised to learn that your original technique seems to be about 30% faster than either of these! I've just done a quick benchmark with "/once/upon/a/time/" and the results are as follows:

Your original = 12s
source.Count = 19s
source.Split = 17s
foreach (from bobwienholt's answer) = 10s

(The times are for 50,000,000 iterations so you're unlikely to notice much difference in the real world.)